In 2012, Kinney landed a starring role in 2012 on Chicago Fire, a drama series that follows the lives of firefighters and paramedics. Kinney plays Lieutenant Kelly Severide on Rescue Squad 3 opposite former House star Jesse Spencer.

Since July 2011, Kinney has been dating pop singer Lady Gaga. They first met while working on the music video shot in Nebraska for her song "You and I" and began dating soon afterwards.[13] They became engaged in February 2015.[14]